"I offer a repair(new DPF) and not a bi-pass as it's the correct repair to carry out. "

Who decides what is & what is not a "correct repair" to carry out?

What constitutes a "correct repair"?

I suppose we should look at what we are trying to achieve when we attempting a repair & what is our goal or motivation?

Are we trying to offer a cost effective, long term & reliable fix, that will allow the owner to use their car reliably & lawfully for a reasonable period, without the likelihood of repeated & costly problems? Or are we simply trying to "bin" the customer off & draw 500 quid for 20 minutes work?

A couple of months ago, I think it is safe to say that a professionally delivered "DPF off" solution, although "questionable", would have ticked all the boxes, in each aspect of my previous statement. After all, if done properly, the car was considered to be lawful at the time, as it should easily pass the annual emissions test as it is currently applied.

It is only now that we are told that the driver is contravening the law, by deliberately using a modified car. So the previous repair route, offered in good faith, is now deemed to be illegal! Who is the bad guy here?

Previously I made reference to, what I consider to be an extremely relevant subject & that is the Vauxhall EGR solution that the manufacturer sought fit for mass release. I am sure that there are other instances too! For example, there are many reported rumours (that's screwed my argument lol ) that many Manufacturers have played with the tolerances of their own Cat Efficiency monitors, to widen the goal posts & allow a more relaxed threshold limit.

What on earth would motivate the manufacturers to manipulate their software in this way? of course we all know that these decisions are driven by balance sheet analysis. 5,000 EGR Valves (just a wild guess) replaced at the expense of the VM, versus a software patch & permanent solution to a headache.

The same argument applies to costly P0420 comebacks.

Of course I am merely sitting on the fence in this discussion & playing devil's advocate. I only ever repair cars "Correctly"

PS These views & opinions are offered in good faith & were believed to be accurate at the time of writing.